Current models of glomerulosclerosis (GS) have yielded little information about the cellular and molecular abnormalities that are critical in the initiation and progression of this disease. The complexity of the kidney and glomerulus make isolation and examination of pure cultured populations of glomerular cells an attractive method for beginning to answer these questions. Unfortunately other models of GS involve extrarenal causes of glomerular injury, including hormonal or cellular events. Because of this, it is quite likely that glomerular cells isolated from these models will not maintain the abnormal behavior in vitro which led to the development of GS in vivo. Mice transgenic for bovine growth hormone develop progressive glomerulosclerosis. We have isolated lines of glomerular mesangial from transgenic mice and have isolated lines of mesangial, endothelial cells and epithelial cells from their normal litter-mates. Our data from the in vivo model indicates that proliferation of mesangial glomerular cells is an early event in the development of GS in transgenic mice, we will evaluate several growth factors on the behavior of individual cells.